The Microsoft Data Access Components (MDAC) provide data access that is independent of data stores, tools, and languages. It provides a high-level, easy-to-use interface, and a low-level, high-performance interface to practically any data store available. You can use this flexibility to integrate diverse data stores and use your choice of tools, applications, and platform services to create the right solutions for your needs.
There are three primary technologies in MDAC.
- ActiveX Data Objects (ADO) is a high-level, easy-to-use interface to OLE DB.
- OLE DB is a low-level, high-performance interface to a variety of data stores. ADO and OLE DB both can work with relational (tabular) and nonrelational (hierarchical or stream) data.
- Finally, Open Database Connectivity (ODBC) is another low-level, high-performance interface that is designed specifically for relational data stores.
ADO is Microsoft's strategic, high-level interface providing consistent, high-performance access to all kinds of data. ADO provides a layer of abstraction between your client or middle-tier application and the low-level OLE DB interfaces. This makes ADO the perfect choice for developers using high level languages who want to access data without having to learn the intricacies of COM and OLE DB.
ADO is powerful and flexible because it can connect to any of several different data providers and still expose the same programming model, regardless of the specific features of any given provider. However, because each data provider is unique, how your application interacts with ADO will vary by data provider (mostly due to slightly different dialects of SQL among database vendors).
As you might have guessed by now, the ADO plugin is based on ADO, but the interface has been simplified even further for use with Flash. Only the most basic functionality has been encapsulated in a handfull of commands. However, those commands make it possible to add, update and delete rows, create and retrieve result sets using industry standard SQL queries, search a database, everything a good database should do.
If you want to use the ADO plugin, you'll need to make sure ADO (and thus MDAC) is installed. The ADO plugin provides the ADO.getVersion and ADO.getProvider commands that you can use to determine whether ADO is supported on a machine before you start blindly making calls to the absent ADO support files through the plugin. That won't do any harm, but the results won't be what you expect. Both of these commands return a failure (error code "3", meaning "No ADO support") if ADO support is not found, giving you a chance to launch the mdac_typ.exe (see details below).
Beginning with Windows 2000, MDAC (including ADO) is now an integrated part of the operating system. Future OS releases will also contain MDAC components. The Microsoft Data Access Components redistribution in English and 18 other languages is available for download on the Microsoft Universal Data Access Web site.
To update Windows 95, Windows 98, Windows NT® 4.0, Windows 2000®, or Windows® Millennium Edition to MDAC 2.8 (the latest version), the redistributable setup program Mdac_typ.exe is available on the UDA Web site. (Note: officially, Windows 95 is no longer supported by Microsoft.)
MDAC is a system component, and installing MDAC should be considered similar to a system upgrade. You cannot remove MDAC without replacing operating system files that were upgraded by the MDAC installer. Many applications, including Microsoft Internet Explorer, Visual Studio, SQL Server, and Office require MDAC for data binding and other application functions. Removing MDAC will negatively impact or break these applications. For more information, see Installing and Redistributing ADO at the Microsoft Developer's Network site.